- A little bit about myself, I was a UCI student like you.
I was a transfer student, so if you're a transfer student,
your first quarter is gonna be rough.
If you want somebody's shoulder to cry on,
you can come talk to me, so it's a really difficult,
difficult transition, I remember coming here.
I had four difficult classes, all my general ed were gone.
I had four difficult classes, I walked around
and I'm like why are all these people smiling?
This is terrible. (laughs)
I can't take it but after one quarter, you just adjust.
So I transferred to UCI, I was kind of thinking,
I was a biochem double major, I was kind of thinking
maybe med school but I don't know
that I was really serious about it
because what I really wanted was to have children,
be able to be home with them, I didn't want them
in daycare so probably an MD would not be
a good idea but I was still a bio major
and then I took organic chemistry
and I just absolutely loved it.
I loved organic chemistry and decided
that I was gonna do research, loved research
and so I went off to MIT for grad school
and super happy, came back here,
took a few years off to have my kids
and came back here and taught as a lecturer.
I've been here ever since so this is really
and this is the greatest job ever, honestly.
So that's my background
and let's move on, okay, questions before we do
a little bit more on the syllabus, anybody?
So I have a handout that we passed out
and that's just to give me a little bit idea about you
and you can fill it out today and turn it in
or you can bring it in on Monday.
So it's gonna give me a little bit of an idea
of where you're coming from, what are your hopes
for this class and how I can help you do well in this class.
Okay, so we've got three TAs,
do you guys want to stand up so we can see?
We have Taylor, we have Tristan and we have Alexa somewhere
in here, over in the back, they're standing in the back.
I guess they don't have a seat.
We'll have to get you guys seats, okay?
So we're gonna be dividing up the discussion sections.
I do do two discussion sections.
I have them marked with an asterisk.
We'll talk about that, I'll show you where that is
in a few minutes and my two discussions
are in this active learning classroom.
That's where all of the bells
and whistles are in that classroom,
so we're gonna do some fun stuff in there too.
We do do Sapling homework, now the way I do Sapling,
I don't like to micromanage you guys.
I basically have one Sapling assignment for each chapter.
So there's a Sapling assignment.
That Sapling assignment is due two days
after we finish lecturing on that chapter, okay?
There are a lot of people that wait until the last minute.
They're long assignments because they're meant
to span two or three weeks, okay?
So if you wait until the last minute,
you're probably not gonna get it done.
What we found with Sapling is that
you get a certain amount of points for Sapling
but the Sapling does have a profound effect
on your grade for the class, okay?
So there are some people who go on
like half an hour before it's due
and suddenly produce all the answers
in half an hour, that would be impossible to do.
You're wasting your time if you do that.
Where you're gonna get the benefit from Sapling
is if you're actually working through the problems, okay?
There are answers out there but it's not gonna do you
any good if you just go and get the answers.
So it's a really valuable resource for you
but again, I'm not gonna have it due every three days,
little assignments here, little assignments there, okay?
We are doing active learning, this is not a flipped class.
We are gonna be doing active learning.
Once, right now, my class is getting filmed
for the first three lectures, I'm gonna be doing
a limited active learning for those first three lectures
because we need to get to a certain point.
So my class is on open cam which is available
to people all over the world, so there's people
all over the world that watch my class.
I get thank yous from all these exotic places
and people thanking me, the first lecture is missing.
The second lecture, you can't even see it
during the first half, it was back in the old days
when I used to use an overhead projector
and so we have this screen on,
we had the overhead projector, you couldn't see anything.
So we're re-filming the first three classes.
After that, I do plan on having active learning,
certainly, every single day but especially on Friday.
So next Friday, we'll be all done with our filming.
We're gonna be doing a lot of drawing resonance structures,
drawing hybrid structures, ranking resonance structures,
all of that kind of stuff, okay?
And so we're gonna practice that.
What I like to do with some of the active learning
is I like to take problems from previous midterms.
So I'll be taking problems from last fall's midterm.
We'll be working them in class.
So I don't post an old midterm,
I'd rather take those problems and work them in class,
okay, so that's gonna help you more.
We will do iClickers, that's gonna happen next week.
I don't have anything set up and so I'll talk more
about that on Monday so nothing you need to worry about
in zero week and let's see what we have here.
Alright, so I sent you an email about the textbook
third, fourth, fifth edition, there is an online.
People don't tend to like the online as much
but if you're interested in the online,
I can try to find the link for that.
I think it's $45 or something like that
to have the online but I think you can actually,
if you get a third edition, you can actually get it cheaper
than that so, and the molecular models
you're gonna need in the fifth week.
So when you take your second midterm,
you'll be able to bring molecular models with you.
So if you don't have them, you're not gonna be
able to bring them with you, okay.
The ChemDraw link is not working, I'm gonna work on that.
Something's wrong with that, alright.
So I have homework assignments from each chapter.
I have them listed for the third, the fourth
and the fifth edition, so what you want to do
and ideally, I mean, I would say this
and maybe my department tutors can correct me on this
or not, I would say that if you want to get an A
in the class, that you should do Sapling
and you should do problems from the end
of the chapter, okay, that's gonna help you do well.
I think it's very hard to get an A
in the class if you just do Sapling, okay?
So that's what I hear, if you find that that's not true,
please let me know because I don't want
to pass around misinformation.
That's just kind of my feeling about that, alright.
So I did make one really big mistake.
In your notes, you've all picked up the notes,
we changed one of the chapters this quarter
and so I don't have it in there
and I feel bad about that because it was too late
for me to do anything about it so what you'll find
is that when you get to the end of your book,
there's chapter seven, chapter seven's in 51B,
I apologize that you had to pay like four cents a page
for that chapter and so what we're gonna be doing
is chapter 14 instead, NMR Spectroscopy,
and when we get to that point, I will post the PDF
of that chapter online for you, okay, alright.
We have two midterms and a final.
We are also gonna have participation points
for things that we do in class.
I take all those points and I add them up together.
I add up the Sapling, the Sapling ends up being
about between 40 and 45 points towards your grade
for all of Sapling, so I get some people
that are very upset, they miss half of Sapling
and Sapling will give your score out of 100.
It is not 100, it is 40, about 45 points
for the entire quarter of Sapling.
So, you know, if you miss certain points,
certain points here, certain points there.
I will tell you that 95% of the students in this class
will get 44 or 45 points on Sapling.
People tend to get really high grades,
so that actual score doesn't really help you
as much as working the problems helps you, okay?
'Cause everybody, you could say that
everybody gets an A in Sapling, okay?
So that's not gonna really move your grade up
when we do grades in the end.
Alright, I'm gonna let you read through this.
We have the exams scanned, if you're new here,
we have exams scanned, when we grade,
we grade on Friday and we get done with grading
on Friday, so we grade all in one day.
I don't know with you guys, let's take a little vote here.
Do you guys want your grades Friday night?
- [Class] Yes.
- Let's see who says yes?
(murmurs)
Who wants them Sunday night?
You want them Friday night, okay, alright.
You know, you don't have to look, right?
You don't have to look.
(laughs)
I suppose, okay, so, also I, you know,
they're in this transition from Triple E
to Canvas, I've had so many problems with Canvas
so I haven't really decided whether I'm gonna load grades
into Triple E or into Canvas, we'll see, okay?
I don't even know because we're gonna do iClicker
through Canvas, it's just, argh,
I've just had so many problems with it this summer.
So I'm hesitant to do that, I know that Triple E works.
So you will get those grades and then we usually bring
the exams, 'cause we grade, it's after five
by the time we finish, we bring the exams on Monday.
We usually get the file back on Thursday night,
like five or six at night, soon as I get that file back,
I post it into the drop box, I know Canvas has a drop box,
I'm just not doing it, I'm just not doing it.
Too close to my bad memories from the summer.
Put it in the drop box and then you can print it out.
If you have a regrade, if there's a mistake,
we make mistakes, you can't grade 400 problems
and not make mistakes, by the way,
when we grade, person A grades problem number one
for every single person in the room.
Person B grades problem two for every single person
in the room, that's the way that grading is made more fair
but you are spending four hours grading one problem
and so you do make mistakes, okay?
So when you make a mistake, you print out your exam,
the offending page, you put your name and ID,
you write what the problem is and you give it to me, okay?
Don't send it by email, those are really large files,
those 400, they're scanned in color.
They're really large files, every time I open up an email
that has one, it goes to my desktop.
I just don't feel like doing that.
So you're gonna do that and don't do it by email, okay?
Discussion sections, I am doing the two that are marked
with an asterisk so that Wednesday at 11
and then Friday at one are my discussions.
You can come to whatever discussion you want.
You can come to all of them, if you want, okay?
No one's gonna do that but you can come
to all of them if you want, so and on test week,
the Friday discussions, well, the nine will be there
but the Friday at one will not be there, okay?
That's my discussion so that means
that if you have Friday at one, you want to go
to an earlier discussion that week,
whatever one you want, okay, I do have a question for you
about the Thursday eight a.m. discussion.
Historically, no one in my class ever wants
to go to an eight a.m. discussion.
So is there anybody who that's the only discussion
they can go to, ah, I don't see any hands.
Okay, so that discussion is now officially gone away.
We're not having the Thursday eight a.m. discussion.
(laughs)
So, just so you know, my son followed in my footsteps.
He came to UCI as a bio major, he wanted to major
in neural bio and when he was 10,
he wanted to major in neural bio
and I said well, you know, and he also wanted to go to UCI
and I said well, you know, if you take bio at UCI,
once you have organic chemistry,
you're not gonna want to be a bio major anymore
and he's like no, I won't, no, I didn't, you know
and so I was like okay, I'm gonna shut up
and just let this unfold and it exactly happened.
He came in as a bio major, took organic chemistry,
he was in my class, I had to get special permission.
He was in my class, he never saw exams, I'm super honest
and he did really well and then he decided that, again,
he wanted to be a chemistry major.
So now he's at MIT in the same group that I was in
with the same advisor, literally following in my footsteps
but a few fun things about MIT for the under grads,
no classes are allowed to start until noon
because they know that most people that are your age,
you know, towards the end of adolescence,
don't do well early in the morning.
No classes are allowed to start until noon.
Grades do not count your first year at all.
When you grade exams, you're not allowed to use a red pen.
Any other color but red, you can't use a red pen
because that makes students upset.
(laughs)
So, just saying, anyway.
Okay, so now you guys are gonna request
that we don't use red pens when we grade, right?
Okay, so we've got department tutoring,
we've got LARC tutoring and there's room
in LARC tutoring if you want to sign up for LARC tutoring.
So, I just wanted to let you know.
They're gonna be coming in and introducing themselves
next week, okay, how to succeed, wow.
That's the big thing, right?
If you treat this class like a math class, okay,
and I would say like a cross between a math class
and a language class and you know
that if you take languages, they usually like you
to come in four or five days a week
'cause you just need a little bit every day.
So it's kind of like that and it's like a math class
in that completely different than in bio.
In bio, you have to memorize a bunch of facts.
In Ochem you do but not the same way.
It's more of a problem solving subject, okay?
So in a bio class, if you're wanting to memorize,
one of the things you might do is copy over your notes
or read the book several times.
You don't want to do that in here.
You want to be working problems.
You want to spend 90% of your time working problems.
You wouldn't think about, in a math class,
you wouldn't think about oh, I'm just gonna go home
and I'm gonna copy over my math notes three times.
You would never do that, right?
So that's the way you want to handle this class.
I have a student who, from a few years back,
and she heard me say that, a lot of people hear me say that
but they don't really ehh, I'm not gonna listen to that
and she was really upset because she got 49
on her first midterm and she came to my office
and said what do I do, how am I gonna get better
in this class, what am I going to do
and I said well, show me what you did
and she said well, here's my notes.
Here's my notes, I copied them over three times
and I thought I knew the material really well
and I said well, take the amount of time
that you spent copying those notes over
and work problems, okay, and she did.
Her second midterm was a 94, she went from a 49
to a 94 by just working problems, okay?
So I really mean it, I'll remind you of that a few times.
Then there's this reference here about
what makes a student successful in organic chemistry
and a study was done and what they found was
that the students who start on day one
and start getting involved in the class,
start working problems when they have something
they don't understand, they come and get help,
they ask one of the TAs, they ask the professor,
maybe the department tutors could help you with it,
those are the people that end up doing really well in Ochem.
Those are the people that end up doing well.
The ones who kind of delay a little bit,
you know, maybe you need a little adrenaline
to get yourself going, those people who delay
and they don't start right away and then they start
to get stressed out when it's midterm week
and oh, now I'm gonna start studying,
those students do not do well and those students
actually end up spending more time studying
than the ones who get an A in the class, okay?
So the important thing is that you start right away.
We also notice, so I'm doing a study on Chem 51P,
the class that I do and we did a study
and I actually presented this summer
at a research conference and what we found
is that the students who did really well in 51A
are the ones that, when they did 51P,
they started right away, okay?
You can see completely different curves
from people who didn't do as well.
They also completed it, they also did Sapling,
they also did all of that, so we found,
it was very illuminating, basically saying
the same thing that this study does, okay?
So we don't want you frantically pulling out your hair
midterm week because you've gotten behind.
So, okay, I would say that's something to take a look at.
Best thing you could do, read the chapters.
So the article is right here and I just took
some quotes from it, read the chapter
before coming to lecture and work the problems
throughout the chapters as you're reading it
and all the additional assigned problems at the end.
The more problems that you do, and do you do Sapling first
or do you do problems first?
It depends on your style, okay, I don't remember.
I think my son did Sapling first and then word problems
at the end of the chapter, okay.
Let's see, where's my curve of forgetting.
Somewhere in here.
- [Young Woman] It's at the bottom.
- It's on the very bottom?
- [Young Woman] I just saw it right there.
- Oh, there we go, curve of forgetting, thank you.
Alright, curve of forgetting, okay,
I really like this curve, okay.
So this is basically talking about how you come in
on day one and you remember everything I've talked about.
You leave this classroom and then you go
to sleep and you can see on day two,
what you remember from what I talked about, okay?
So, when you're sleeping, your body's deciding
what am I gonna put into longterm memory
and what am I gonna not, I'm looking for my pointer.
It's in here somewhere.
(rustles)
Somewhere in here, oh, here it is.
So I got this cool, little, green laser pointer.
Let's see if it's gonna work here.
Okay, here's day one, that's how much you remember.
So while you sleep, your body decides,
your brain decides what it's gonna remember, okay?
So you actually need that information, okay,
but if you just take 10 minutes on day two
and you look over that information
or, in this case, you work a couple problems
that deal with that information,
that's how much you're gonna remember, okay?
And then, you know, the next time you do it
in five minutes, two to four minutes, okay?
So that's just one lecture but every time you come in here,
you get another lecture, so you got
to be continually doing this and day 30,
that's when we have a midterm.
You don't want to have to relearn all material
that we did for 30 days, you don't want to do that.
So, by doing a little bit each day,
it makes it easier for you, okay?
So just wanted to show you that.
Okay, no, I want to go back to that.
I just closed it, okay, anyway, letters of recommendation.
So if you, I'm gonna see a bunch of you
a couple years from now when you decide you want
to go to dental school and medical school, pharmacy
and if you want to come ask me
for a letter of recommendation,
there's a little section at the very bottom
that talks about what you need to do, okay?
Questions, do you have any questions about me, anything?
I was not, yeah, go ahead.
- [Male Student] Where are you from?
- Mostly from California, we moved to California
when I was seven, my dad was in the service
before then so I have a lot of places
but I'm mostly from California.
Any other questions, yeah, over here.
- [Female Student] Will parts of exams
be on a Scantron or...?
- There's not Scantrons, no, yeah,
that's why we have a team that grades.
If I had to grade all of the exams myself,
I would have to sit on a desk for an entire week
without doing anything but grade exams.
So, yeah, no, it's not Scantron.
We can't really do Scantron, any other questions?
- [Woman] Yeah.
- Yeah.
- [Woman] Do you want our names or student ID
on this or will it be anonymous?
- Oh, it's anonymous, yeah, no, I don't want
your name or ID on that, yeah, over here?
- [Young Man] What was it about Ochem
that made you want to do it?
- Organic synthesis, I just love it so much.
(laughs)
Yeah, it's so, I just love it, yeah.
- [Male Student] Is this class curved or...
- It is curved, yes, it is curved
but it's not a standard curve.
It's a better curve than a standard curve.
(laughs)
(claps)
I mean, let's just say, for instance, it won't happen
but let's just say for instance,
let's just say, you know, I've been teaching a long time.
I know how difficult an exam is.
I mean, I know if an exam is a reasonable exam, you know,
and let's just say everyone in the class got 80 or 90
on that midterm, there's nobody getting a D or an F
or even a C on that, you understand?
So the curve is adjusted based on how strong the class is,
okay, so if it's a really strong class,
then I will give more A's and B's, okay?
And a standard curve, nobody has a standard curve.
A standard curve is 15% A's and 15% F's,
20% B's, 20% D's and then C's are in the middle
and that's the largest, that's a real curve
so we don't use a real curve.
Typically, this class, the mean will be like a B minus,
C plus-ish in that range, okay, more questions?
By the way, when I took Ochem,
I was not the top student in the class.
I wasn't, I mean, some of department tutors
did better than I did in Ochem.
I got A's but I worked really, really hard
and I didn't have anybody to help me.
I was the first in my family to do chemistry
and so I had nobody to help me.
You know, my son, gosh, he lives with somebody
who he could ask questions, he would never
ask me questions though, he did not want
to ask me questions, he wanted to do it himself.
So, yeah, I don't think he really had
an advantage in that way, yeah?
- [Student] How long you been teaching here?
- 24-ish years, 23, 24 years, yeah?
(claps)
So, yeah, I know.
Yeah.
So I know the difficulty level of a test, you know,
when I give it to you guys, alright, more questions?
Shall we get started doing some chemistry, yeah, okay.
(murmurs)
Let's see if that works.
So, by the way, this is not a good position for your back.
Next time I come here, I'm gonna have something
to lift this up for me 'cause I will be in a wheelchair
and a back brace before too long if I continue to do this.
Anyway, I just wanted to show you some,
so, here we talk about the chemistry of compounds
that contain carbon and so that's greater than 95%
of all chemical compounds are organic,
so a super-important topic to talk about.
I'm showing you some examples
of naturally occurring molecules,
you're not memorizing these, please do not memorize these.
These are just to give you some examples
and so we have some little shortcuts
that we're gonna be talking about very shortly
when you write structures, so we're leaving some carbons
out here, we're leaving some things out here
but this is right here, this is capsaicin.
I have birds in my backyard and if you give them birdseed
that's covered in capsaicin, you don't get rats
and you don't get squirrels 'cause birds can't taste
the capsaicin but the rats and the squirrels don't like it.
So that's capsaicin, this is oxytocin, very large molecule.
This is sucrose or table sugar
and this is morphine, okay, so as we know,
we have a painkiller crisis epidemic
of addiction to painkillers so that's morphine
and some of the other compounds.
We'll be talking about those coming up
in the third quarter, some variations on morphine,
okay, and this molecule right here
is so large it is a 517 amino acids.
So we can't draw out all those amino acids
so you see things written as ribbons.
This is ALDH2, aldehyde dehydrogenase two,
and about 36% of East Asians have a deficiency
in this enzyme, so have you ever heard
of Asian flush when you drink alcohol, okay?
If you get Asian flush, you shouldn't drink alcohol,
honestly, if you do, you're at a higher risk
for esophageal and stomach cancer
and those are not good cancers
to have because there's only like a 15% survival rate
for five years with esophageal cancer.
They are though, not to make you really depressed
and all I can't go on without my alcohol.
They are working on things that you can take
that alleviate this problem, so things that you can take
when you drink so that you still can drink
'cause you're accumulating acetaldehyde
in your brain when you drink alcohol, okay?
So it's not working efficiently, alright.
I'm gonna have to figure out how
to get this to scroll better, okay.
Let's go up, again, alright, synthetic organic molecules,
rubbers, dyes, pesticides, rayon,
nylon, drugs, this is crystal violet.
(laughs)
Okay, there's the picture of crystal violet
and if you have the majors honors lab,
we made crystal violet, it's a really cool lab.
This is polystyrene, again, we're using some shortcuts
when we're writing these molecules
and we'll be talking about those next week.
This is DDT and sometimes, for some reason,
I'm gonna work on this file but sometimes,
these are all drawn on a Mac and sometimes,
when I go here, we're missing bonds
that should not be missing on your page
and then this is Lipitor, okay,
so lots of drugs, very important,
used to treat high cholesterol, alright.
Structure determines reactivity, that's the key.
So we are gonna spend a huge amount of time
talking about structure, everything that you ever needed
to know about these structures
and then, once we know everything about structure,
we're gonna be using that to determine reactivity, okay?
So it says something that's really different
about Ochem than Gchem, in Gchem,
you never had to really predict reactivity.
Maybe if you were looking at oxidation reduction,
you could figure out which way the reaction
would be favored or something like that
but we'll actually be doing predicting reactions here.
So we have to spend a long time learning about structure
and so really, the way this class works is
the first quarter, we build the foundation.
We spend the whole entire time building the foundation
and then we get into second quarter
and now we're gonna start building
this really tall building.
Everything builds upon everything.
So it's like we're gonna build the first floor first
and then the second and then the second and then the second.
So if you have a shaky foundation,
that building is not going to stand, okay?
So I feel like I do a really job
of giving students a good foundation
and if I give you a good foundation
then, you know, you may decide you want
to go to another class, that's fine,
you'll have a good foundation to do well, okay?
So that's what I do but it kind of reminded me
of last year when they were building the student housing
and it seemed like for a long time,
they're moving around the dirt and moving around the dirt,
working on the foundation and as soon
as they get that foundation done,
then you start seeing the building go up really fast
and that's a really good analogy.
That building does go up really fast, okay?
So we're just gonna work on building a good foundation.
So the other thing is I assume nothing.
I assume no previous knowledge, honestly.
I start from the beginning, there's a lot of people
who will skip chapter one entirely and just move on, okay?
There's a lot in chapter one that you need to know.
Everybody's coming in here with a different background.
That's why I started that 51P class
to kind of even the playing field a little bit
but not everybody here has taken that class
and so I'm not gonna assume that you know what I taught
in that class because some people couldn't do it, okay?
So I'm gonna start off, you're probably kind
of rolling your heads but just enjoy it.
Enjoy when you know everything
because it will not last for long.
(laughs)
Okay, so just enjoy it and the reason I talk
about this at all on this first page
is because we do talk about isotopes
and if I don't talk about this,
people don't know what I'm talking about
when I talk about isotopes, okay?
So all matter's composed of the same building blocks
called atoms, oh my, this is where we roll our eyes.
So an atom's very, very dense, this is beyond
our comprehension, how dense and so I like this fun fact.
If the nucleus was the size of a ping pong ball,
it would have a mass of 2.5 billion tons.
That's how dense it is and the electrons would be,
on average, a mile away, so very far away.
That's it, so the mass of the proton
is approximately one atomic mass unit.
Mass of a neutron is approximately one atomic mass unit
and the mass of electron is approximately very, very small,
point one, two, three, four zeros,
.00005 AMUs and the atomic number gives the number
of protons in the nucleus and the mass number
gives the sum of the protons and the neutrons.
So let's look at carbon, our favorite atom here,
atomic number six and the mass number is 12.011,
okay, so that means in our nucleus,
we have six protons, the atomic number tells us that.
The neutrons are gonna vary, if the mass is 12,
that means that we have six neutrons
and that we also have, so that's our nucleus,
We also have six electrons outside the nucleus.
Okay and here's where we get to isotopes.
Why does carbon have an uneven mass number?
If the mass of a proton is about one,
the mass of a neutron is about one,
why are we at 12.011 and that's because carbon,
naturally occurring carbon has isotopes.
So we have carbon 12, so when I write the mass number,
I'm writing it up and to the left, okay?
That tells you that I have a carbon 12 nucleus,
then that would be six protons, six neutrons,
that's the one that we just talked about.
Six protons, six neutrons and that's in a natural sample,
we would have 98.8% carbon 12.
You're not memorizing these numbers, okay?
Carbon-13, at the end of the quarter,
we're gonna talk about carbon-13 NMR
so you kind of need to know what that means.
We have six protons, the protons don't change.
The neutrons change, we have seven neutrons
and those seven and six adds up to 13.
So that's our nucleus and that's 1.11%,
there's also a little bit of carbon-14,
six protons, eight neutrons and this is a trace.
There's an actual number for this.
I don't know what that number is
but there's a trace of that and so,
this is also unstable, it's an unstable nucleus,
therefore it's radioactive.
It has a very long half life, it has a half life
of 5730 years.
So if you have a natural sample of carbon
and you take, let's say, you cut down a tree.
That tree is gonna have a fixed percentage of carbon-14.
That number's not gonna change, okay,
while the plant is alive but as soon as it's dead,
that's gonna be radioactive, it's gonna lose some
of that carbon-14 and that's how we used
to date artifacts, so used to date artifacts.
Alright, so I'm not gonna go into that
but that's how carbon-14 is used to date artifacts
if you're interested in that, if you have a pot
from a site and it has half the number of carbon-14
than something's that just been made,
that means that it is 5730 years old.
So that's basically what the idea is.
Questions so far, alright, so another thing
that's really different about this than Gchem
is that in Gchem when you were drawing Lewis Structures
and you had a charge, you would take the brackets
and you put the charge outside of the brackets, okay?
When you were drawing Lewis Structures.
We don't do that, we don't do the brackets
and the charge outside the brackets.
We put the charges on the actual atom that it belongs to
and if there's more than one charge,
if there's a neutral atom but you have a positive charge
and a negative charge, we want the charge on that atom.
We need to know where that charge is,
again, because we're in the business
of being able to predict reactivity
and that actually helps us to predict reactivity.
So let's look at sodium, if you have NA+, okay,
common way to find sodium, it's number 11,
atomic number 11 so we have 11 protons,
it's about 23 so that means the major isotope,
we have about 12 neutrons and we have 10 electrons,
okay, we've lost an electron so we only have 10 electrons
and we have an overall positive charge
and CL-, also very common way to find sodium
and by the way, I do put circles around my charges usually
and that's because, well, we'll see coming up.
You're not required to but I do put circles around it.
So CL-, 17 protons, we know that
because it's atomic number 17, we have 18 neutrons,
18 electrons, so we have one extra electron
so therefore we have a negative charge.
Okay, so so far so good, any questions?
Again, we're starting at the beginning here, yes?
- [Female Student] Is it 10 electrons?
- Excuse me?
- [Female Student] Is it 10 electrons or 18?
- Well, neutral sodium, is it right here?
Is this what you had a question on?
- [Female Student] It says 10 on the board.
- Oh, no, I didn't, I'm sorry, I wrote, I said.
God, yes, thank you.
(laughs)
Awesome, okay, any other questions?
I like it when you guys catch my mistakes
because otherwise, I'll get a bunch of emails about it.
Better to just straighten it out here.
Alright, let's look at bonding.
Bonding is the joining of two atoms.
Through bonding, atoms achieve a complete octet.
Outer shell of valence electrons, okay?
The octet rule, atoms transfer or share electrons
in such a way to obtain a filled shell, okay?
So the atoms are happy when they have a filled shell.
So they're gonna do a lot of different things
to try to obtain a filled shell.
So for hydrogen, a filled valence shell is two electrons
for a filled valence shell.
So that's actually not the octet rule,
that's the duet rule but you know,
we're not gonna worry too much about that.
Hydrogen's happy when it has two electrons
in its valence shell and second row
of elements, which is 95% of what we do
in this class is second row of elements, okay,
so that's gonna be eight electrons
for a filled valence shell.
Okay and so, when we have something in the second row
that has a filled valence shell,
it's gonna have neon configuration
and hydrogen, when it has a filled shell,
has a helium configuration.
Alright, so there's two ways that atoms can interact
to obtain, so these are both noble gases,
a filled shell is a noble gas configuration
and there's different ways that atoms can
attain a noble gas configuration
and so ionic bonding and covalent bonding.
So let's look at both of them.
We don't do too much with ionic bonding
but let's talk about it anyway.
Atoms obtain a filled shell by transferring electrons.
So when you have ionic bonds, an electron
is completely transferred from one atom to the other.
Okay, so for example, we have lithium.
Lithium picked straight off the periodic table
has one electron, fluorine, if you pick that
straight off the periodic table, it has seven electrons
and so what happens is, when you combine the two,
what happens is the lithium is gonna
donate its electrons to the fluorine.
I'm gonna use an arrow, we're really big on arrows, okay?
I'm using a single-headed arrow,
it's called a fishhook arrow, because I'm trying
to show movement of one electron.
Most of the time in this class,
we're gonna use double-headed arrows
that show movement of two electrons
but this is a fishhook arrow.
Fishhook arrow shows movement of one electron.
Alright, so when lithium transfers its electron to fluorine,
we get lithium plus and F-, fluoride ion.
So the F- has the neon configuration
and the lithium has a helium configuration.
So noble gas configuration, everyone's happy
and then the actual ionic bond is
that electrostatic attraction with the positive
and the negative, it's not the transferring the electron.
Okay, so they're held together by electrostatic interaction.
Electrostatic interaction in a crystal lattice.
Alright, so there's the ionic bond for you.
We don't do too much with ionic bonding.
Most of our stuff is gonna be covalent bonding.
Ionic bonding is seen when we have atoms
with widely differing electro-negativities, okay?
Widely differing electro-negativities.
So this is one of the trends that you talked about
in Gchem and one of the trends that you're gonna need
to know and that's the electro-negativity trends.
So, as we move to the right across any row
on the periodic table, we have
increasing electro-negativity
and as we go up, I'm not gonna put this to the right
because we really won't see electro-negativities
for the noble gases, we're just gonna go this way, okay?
That's also increasing electro-negativity.
So that means that fluorine is the gonna be the one
that's the most electro-negative, okay?
You do not need to memorize these numbers
for electro-negativity, if you need them,
I'll provide them but I do want you to know the trend.
Alright, so if the electro-negativity is greater
than about 1.8, about because there's some exceptions
to this, we want to say about instead of exactly,
the electron's gonna be transferred completely
and not shared, okay, so lithium has an electro-negativity
of one and fluorine has an electro-negativity of four.
The difference is three,
is 3.0, therefore we're gonna have
an ionic bond, so when we have covalently bonded compounds,
those are closer in electro-negativity
but that's time, we'll stop right there
and we will continue this on Monday.
I hope you guys have a fantastic weekend.
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